[Band map in Japan]

[Best 10]

The (001) surface is non-polarized in which the numbers of carbon and TM atoms are equal each other on the outermost layer. In this study, the transition metal (TM) carbide surface (periodic super cell model including 9 TM-C layers as a slab and vaccum region as the same thickness of slab) are optimized only in a [001] direction. The surface electronic structures in the optimized structures are metallic in all cases. (Bulk TiC[rock salt structure] is also metalic.) In most cases, the carbon atoms are displaceed outward and TM atoms inward on the top layer with and without PCC, except for the case of TiC without PCC. This trend for TiC and TaC agrees with above theoretical results(PWC). Moreover, charge densities of surfaces, work function, etc. are calculated in this study(4/25, 2000). As for TM pseudopotentials, it is found that considering a partial core correction(PCC, S. G. Louie, S. Froyen and M. L. Cohen, Phys. Rev. B26, 1738(1982)) is very important in the structural optimization.

Transition metal nitride surfaces (TiN, ZrN, NbN, HfN and TaN(001)-1x1) have also been investigated [2].

Reference:

[1] K. Kobayashi: Jpn. J. Appl. Phys. Vol. 39, No. 7B (2000) 4311.

[2] K. Kobayashi: Surface Science

[3] K. Kobayashi, "First-principles study of the Ti

[4]K. Kobayashi, N. Kobayashi, and K. Hirose, "First-Principles Study of TiN/MgO Interfaces", e-J. Surf. Sci. Nanotech., 12 (2014) 230 - 237 (ACSIN-12 & ICSPM21) [DOI: 10.1380/ejssnt.2014.230]

[5]K. Kobayashi, H. Takaki, N. Kobayashi, and K. Hirose, "Electronic Band Structure of Various TiN/MgO Superlattices", JPS Conf. Proc. 5 (2015) 011013 (CSW2014).

[6]Hirokazu Takaki, Kazuaki Kobayashi, Masato Shimono, Nobuhiko Kobayashi and Kenji Hirose, "First-principles calculations of thermoelectric properties of TiN/MgO superlattices - the route for enhancement of thermoelectric effects in artificial nanostructures", J. Appl. Phys. 119 (2016) 014302.

[Figure](png,30KB,TiC(001)1x1 surface [structural optimized], Green and red circles are C and Ti, respectively.)

It is found that the critical pressures are about 70GPa for Ga and 120GPa for In[1](Japanese version),[2](Abstract,large postscript file , 160kbytes),(Proceedings of AIRAPT-16 and HPCJ-38, Vol. 7, 196-198(1998),Very Large postscript file,623kb), K. Takemura, K. Kobayashi and M. Arai, Phys. Rev. B

On the other hand, it should be noted that the actual shallow d core states for Ga and In are deeper than those calculated on the basis of the local density approximation(LDA) in the density functional theory[refer to E. Wigner, Phys. Rev. 46, 1002(1934), W. Kohn and L. J. Sham, Phys Rev. 140, A1133(1965), P. Hohenberg and W. Kohn, Phys. Rev. 136, B864(1964)].

Recently(1/20, 1998), the author have studied to calculate electronic properties of Tl under high-pressure conditions. The critical pressure of overlap between valence 6s- and core 5d-states for Tl is 10 GPa because of a very shallow core d-state. This figure(png file, 20KB) is a variation of electronic band structures of Tl from 1 to 128 GPa.

These critical pressures may be underestimated on the comparison with the actual critical pressures in which the bottom of the valence states touches the top of the shallow core states, respctively. This suggests that it is necessary to consider beyond LDA calculation(GGA,SIC,GW-approximation,etc.).

[Important papers]

[Memorandom]

[Materials]

[DFT,LDA]

Main [site]

BandStructure.jp [site]

Electronic and lattice properties are obtained by using the FPMD. In detail, please see references[1][2][3].

[1] K. Kobayashi and K. Yamamoto, J. Phys. Soc. Jpn., Vol. 70, No. 7 (2001) 1861.

[2] K. Kobayashi and K. Yamamoto, J. Phys. Soc. Jpn, Vol. 71, No. 2 (2002) 397.

[3] K. Kobayashi, M. Arai and K. Yamamoto, J. Phys. Soc. Jpn. 72, No. 11 (2003) 2886.

We found the lattice anomalies of LiBC and HBC under anisotropic compression (

In detail, please see references[1]-[6].

[1] K. Kobayashi and M. Arai, "LiBC and related compounds under high pressure", Physica C 388 - 389 (2003) 201 - 202 (LT23).

[2] K. Kobayashi and M. Arai, "Lattice Anomaly of LiBC and Related Compounds under Anisotropic Compression", Journal of the Physical Society of Japan, Vol. 72, No. 2 (2003) 217.

[3] Related paper: K. Kobayashi, M. Arai and K. Yamamoto, J. Phys. Soc. Jpn. 72, No. 11 (2003) 2886.

[4] K. Kobayashi and M. Arai, Mater. Trans., Vol. 45, No. 5, (2004) 1465 - 1468.

[5] K. Kobayashi and M. Arai, Molecular Simulation, Vol. 30, No. 13 -15 (2004) 981 - 986 [ICMS-CSW2004].

[6] K. Kobayashi, M. Arai and T. Sasaki, "Lattice Anomalies of

Some of them have characteristic unoccupied flat bands close to the Fermi level at the Γ -

In detail, please see references[1]-[3].

[1]K. Kobayashi, Y. Zenitani and J. Akimitsu, "First-Principles Study of C

[2]K. Kobayashi, M. Arai and K. Yamamoto, "First-principles study of C

[3]K. Kobayashi, M. Arai and K. Yamamoto, "First-principles study of C

Related [page](B-, C- and BC-compounds, go to bandstructure.jp)

VBM: Valence band maximum CBM: Conduction band minimum

The electronic band structure of [

In detail, please see the reference[1].

[1]K. Kobayashi, K. Watanabe and T. Taniguchi, "First-principles study of various

The electronic band structure of [5H-BN](png, 40 KB, bandstructure.jp).

In detail, please see the reference[1].

[1]K. Kobayashi and S. Komatsu, "First-principles study of 5H-BN", Journal of the Physical Society of Japan, Vol. 76, No. 11 (2007) 113707.

6H polytype has two crystal structures as ABCACB and ABCBCB. Crystal symmetries of ABCACB and ABCBCB are P6

In addition, we have investigate 10H-BN and 10H-AlN[2]. The 10H polytype has 58 structures. We choose four polytype structures whose hexagonalities (

Furthermore, we have calculated 8H-, 10H, 12H- and 18H-SiC polytypes[5]. In this study, it is found that 10H-SiC(ABCACBCACB,

In detail, please see the reference[1].

[1]K. Kobayashi and S. Komatsu, "First-principles study of BN, SiC, and AlN polytypes", Journal of the Physical Society of Japan, Vol. 77, No. 8 (2008) 084703.

[2]K. Kobayashi and S. Komatsu, "First-principles study of 10H-BN and 10H-AlN", Journal of the Physical Society of Japan, Vol. 78, No. 4 (2009) 044706.

[3]K. Kobayashi and S. Komatsu, "First-Principles Study of 6H-AlN under various pressure conditions", J. Phys.: Conf. Ser. 215, 012111(2010).

[4]K. Kobayashi and S. Komatsu: "First-Principles Study of 30H-BN polytypes", Materials Transactions, Vol. 51, No. 9 (2010) 1497[6H-BN, 30H-BN].

[5]K. Kobayashi and S. Komatsu, "First-Principles Study of 8H-, 10H-, 12H-, and 18H-SiC Polytypes", Journal of the Physical Society of Japan, Vol. 81, No. 2 (2012) 024714[8H-SiC][10H-SiC][12H-SiC][18H-SiC].

[6]K. Kobayashi and S. Komatsu, "First-Principles Study of Various BN, SiC, and AlN polytypes", Trans. MRS-J, Vol. 37, 583-588 (2012)[IUMRS-ICEM2012][20H-SiC][30H-AlN][48H-BN].

[7]K. Kobayashi and S. Komatsu, "First-Principles Study of AlBN and Related Polytypes", Trans. MRS-J, Vol. 38[3], 485-492 (2013)[4H-AlBN][4H-AlAsN][4H-AlPN][2H-, 3H-, 5H-, 6H-, and 12H-AlBN][3x2H-AlBN].

Reprints of [10H-SiC][30H-BN][10H-BN(10H-AlN)][6H-AlN][5H-BN][

(References)

[BH] U. von Barth and L. Hedin, J. Phys. C

[PBE] J. P. Perdew, K. Burke, and M. Ernzerhof, Phys. Rev. Lett.

Please see the references [4][5][6].

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